Help! RAM Upgrade Mystery for Pavillion 7955!

When I bought this computer in 2002, I upgraded the 256MB RAM to 512MB with no problem. What came in the computer looked like this:

What I ordered was 256 MB; 168-pin PC133. It had 8 black rectangles, but no space in the middle. When installed back in 2002 along side the already intalled RAMin the 2nd of three RAM slots, I got 512MB of RAM and have been getting it ever since.

Last week, I purchased 3 sticks of 512MB PC133 168-pin to upgrade the 7955 to the full 1.5GB in its three slots. The RAM I purchased looked exactly like the RAM I purchased in 2002, 8 rectangles with no space in the middle. I had some curious results when installing these:

1. Computer would not turn on. It made a repeating beep noise. It would beep for like 4 seconds, go silent, beep for 4 seconds, go silent..(etc).

2. When I used any combination of the 512MB (1, 2, or 3), same result as #1.

3. When I replaced the original two sticks of 256 MB and installed a 512MB, same result as #1. I tried every combination 2x512 and 1x256. 1x512 and 1x256; no dice.

I am guessing I have the wrong RAM, but I bought what the HP specifications for the Pavillion 7955 said to buy.

Here was what was weird. After trying all conbinations, I gave up and closed the tower up with the two original 256MB sticks installed. During start up, I noticed I was only getting 256MB of RAM. After opening the PC back up, I noticed that I had the original 256 stick in the 2nd slot and the 2002 added 256 stick in the first slot. After exchanging them, I was back to 512MB. Remember, the oginal RAM has a space in the middle of therectangles and the 2002 added stick has no space.

Should just return all three sticks of the 512MB PC133 I bought and exchange them for the same thing but modules that have the space in between the black rectanges? If this is the case, why does the computer get 512 MB with its current configuration with one module with a space in between and one module without the space? Also, what is going on with the slot thing where I get 512MB of RAM if my 2x256 sticks are plugged in a certain way?

Each memory slot can hold SDRAM, PC133 with a maximum of 512MB per slot.*

*Not to exceed manufacturer supported memory.

Have you made sure that the memory slots were clear before inserting the new memory? Made sure there was no dust in the way? Make sure the memory is seated in the slot completely and even so that it's detected. What brand/specs of memory had you purchased?

Re: Help! RAM Upgrade Mystery for Pavillion 7955!

I once had a 7955 and I can tell you that it is very picky when it comes to ram, especially anything over 256. The only 512 that would ever work in mine was low density ram, high density would not boot. (Low density = Chips on both sides of stick)

I tried several brands with no luck...till I finally bought from Crucial.

**Click Accept as Solution on a Reply that solves your issue to help others********Clicking the Thumbs-Up button is a way to say -Thanks!.******